Early 930 engines came with Dilivar studs top and bottom.
They should be replaced.
If you're going through the trouble of removing all the studs, why not use the best.
Supertec head stud kits are well worth the cost in quality, ease of engine assembly, reliability and cylinder to head stability.
The best selling studs on Pelican Parts.
1979 Porsche 930 Turbo Coupe - Cylinder Head & Valvetrain - Page 6